Radio beacon system



Sept. 17, 1935. c. w. HANsELL RADIO BEACON SYSTEM Filed Aug. 8, 1930 3 Sheets-Sheet 1 .Wohin-3DO:

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. INVENTOR CLARENCE W. HNSELL BY '7% AfTToRN Y Sept. 17, 1935. c. w. HANsELL 2,014,732

RADIO BEACON SYSTEM l Filed Aug. 8, 195o s sheets-Sheet 2 AMPur-:ER E293 5 MonuLA-roi A TONE GENERATOR GENFRATUR MOTR v f Jig, 5

POWA'A 300. fl/Illy ATTORNEY Sept 17, 1935.

c. w. HANsELL RADIO BEACON SYSTEM Filed Aug. 8, 195o 3 Sheets-Sheet 3v Patented Sept. 17, 1.935

UNITED' STATES-PATENT OFFICE molo BEACON SYSTEM Clarence W. Hansell, Port Jefferson, N. Y., as-

signor to Radio Corporation of America, a corporation of Delaware 'Application August s, 1930, seria No. Massa is claims. (ci. 25o-11i This invention'relates to improvementsin or connected with directional radio apparatus and the like and in particular to an improved method and means for producing unidirectional radio transmission from an aerial system the radiations of which rotate continuously so 'as to lie successively along all points ofthe compass. l

'The present method and apparatus for producing radiations as described above is primarily for use at stations which-serve to supply moving crafts as -for instance marine' ships or airships with information as to their position lrelative to the transmitting station at a particular time.

The use of radio beacons to guide moving craft is known in the art. In fact, at the-present time the Bureau of Light Houses ofthe United States J Government installing systems whereby fixed radio beams are transmitted for thefpurpose of informing aircraft of their positions. stations now known for giving aircraft or ships the proper course are useful 'only for marking out either onexed courseor a plurality of xed courses. This necessitates duplication of stations in all cases where a. considerable number of courses are required. This, of course. requires duplication of the entire system, and obviously results in a great cost ofmoney, and a waste of ground space where all available space is necesv sary for landing aircraft. Also a plane not on one of the xed cours, and perhaps not intended to be on it, has no way for determining what its direction tothe beacon actually is.

The -primary object of the present invention is to provide a beacon 'system in which the number of courses which can be marked out is Another object of the present invention is to provide a radiating system-in which the radiations Aare of the character' known as unilateral and in which every point on the unilateral char- 40 acteris'tlc curve ofthe radiation as for instance.

the null point is caused to rotate 'continuously at any desired predetermined speed to lie .successively along all of the compass points.

A further object of the present invention is to provide'an aerial system of the novelv nature described above to be used with receivers with which b y means of a novel indicating arrangement a craft carrying such'a receiver may determine at anyinstant its position relative to the source of radiation.

The above objects are attained in accordance with the present invention by' providing a xed radiating system comprising a plurality of frame aerials located at angles with respect to each 05 other and a vertical aerial, allfof which aerials Beacon' are energized atthe same carrier frequency and in which the amplitude of the potential applied to the frame aerials varies cyclicly within certain limits at a predetermined frequency. 'Ihe effect is much the same as that which can be obtained 5 by actually rotating a single frame aerial which is radiating energy and simultaneously causing energy of the same frequency to be radiated from a vertical'aerial so that the resulting field is represented by a cardioid which rotates with the ro- 10 tation of the frame aerial. In the present invention the rate of rotation of the cardioid radiatedv vwill ofcourse depend on the rate at which theam- 'though addingto that of the vertical in the oppo- 20- site direction. Also the phase relation of the radio frequency currents in the frames with respect to the current in thevertical must be alike.

Now, if this rotating transmission is modulated at an audio frequency rate which varies continu- 25 ously between certain limits in accordance with the instantaneous direction of radiation, then the direction of the beacon vwill be indicated in a receiver by the absence of a certain audiofrequently in the receiver-which indication will oc- 3 cur when the null point of the radiation curve is pointed towards the receiver.

In onemodiflcation of my invention Ythe aerial system comprises a plurality of loopsas for instance 3 loops set an angle of 120 degrees with 35' respect to each other and a vertical aerial sym-f metrically arranged with respect to the loops. 'I'he fraine aerials and vertical aerial are each energized from separate thermionic ampliera excited by means of a single master oscillation 4 generator so that the frequency of the oscillations in the loops andinthe vertical aerial is the same. The anodes of the thermionic amplifiers are suppliedby constant direct current voltage from a high voltagesource. The amplitude of 45 the effective voltage on the plate of each of the thermionic amplifiers associated with the frame aerials is .varled cyclicly between certain limits by means of three phase alternating cm'rent supplied from any source as for instance a generator. 5 This varying of the amplitude of the plate potential of the ampliers connected with the loops will cause the energyradlated from the system to rotate about the system. 'Die frequency ofthe radiofrequencycurrenisfedtoeachoftheamtions furnished from the control oscillator may be keyed or modulated at an audio rate the pitch of which varies in an approximately linear fashion between predetermined limits in synchronism with the rotation of power between the three amplifiers and the corresponding frame aerials connected therewith. This results in that as the -radiation pattern, 'e. g. the cardiid, rotates` the tone pitch of the signal heard by a distant receiver varies with the rotation of said cardioid and has a diierent definite value for each position of the radiation pattern. If at the time a given audio frequency modulation or pitch is present the distant receiving station is"at the zero or null point on the radiation pattern then this modulation frequency or pitch vwill not be heard in the receiver but all other frequencies will be heard in the receiver once during each rotation of the pattern.

More in detail for each a'ngle at which a radio receiving station may be located with respect to the layout of the antenna system, there will be some particular audio frequency modulation which will not appear in the receiver arranged to respond to the signal modulation on the carrier. Consequently, if the receiving operator has an instrument such as a reed indicator connecting to the output circuit of his receiver, which indicator carries a frequency scale matching the frequency range covered by the modulating frequency at the transmitter then the indicator will instantly designate the direction of the trans.

mitting station by the fact that the reed or group of reeds attuned to that particular frequency fails to vibrate or vibrates with less amplitude than the other reeds. This will indicate the direction of the beacon system from the receiver.

l In a modification of the arrangement briey described labove the aerial system may comprise 'a plurality of vertical aerials properly spaced relative to each other and to another vertical aerial to obtain the proper directive effect, all of the aerials being fed at the same frequency while the last aerial is vfed degrees in phase ahead of the rst mentioned aerials. The energizing circuits in this modication may be similar to the ones described above.

A further modification contemplates the use of an aerial system comprising a vertical aerial and a plurality of fixed frame aerials arrangedA at angles with respect to each other. `Each of the frame aerials is connected to a field winding. The eld windings are each associated with a rotatable Winding which is energized by currentv from a thermionic amplier modulator associated with the master oscillator on the one hand and a y wherein the rotating directional eld has a sharp maximum and the maximum isusedto determine the direction. In operation the indicator used will indicate the direction of Ythe signal source to which it is tuned by that one or more of the reeds tunedrto one or a narrow band of frequencies will vibrate more pronounced than the others and will thereby give an indication of the direction of the source of the signals.

The novel features which are considered characteristic of the present invention are s'et forth 5' with particularity in the claims appended at the end of the specification.4 The invention, however, both as to-organization and method of operation together with numerous objects and advantages, will be better understood from the fol- 10 `lowing detailed description and therefrom when read in connection with the annexed drawings throughout which like reference characters indicate like parts and in which;

accordance with the present invention,

Figure 6 shows a curve wherein the frequency of the pitch modulation is plotted relative to the 30 4vnumber of rotations ofthe radiating curve.

Figure 7' shows an indicating device ton be associated with the output circuit of a receiver adapted to receive signals from the above directional aerial system, while;

Figure 8 shows a novel receiver adapted to be used with the radiating system of the prior iigures.

Referring to the drawings and in particular to Figure 1 thereof-the aerial` system comprises 40 a plurality of loops I, 2 and 3 located at an angle with respect to each other, which for purposes of illustration will be taken as 'degrees. A vertical aerial 4 is located adjacent the loops being shown symmetrically located with Vrespect to the 45 loops. Each of the aforementioned `radiating members are connected to thermionic amplifiers 5, 6,1 and 8 respectively. The input'elements of all said thermionic amplifiers are connected in parallel with the output elements-of a thermionic ,-,3 ampliermodulator 9 which is excited on the one hand by oscillations from a crystal controlled master oscillation generator I0, and on the other band, by modulating currents from the commutator on a variable pitch wheel II` The pitch 5;; of the modulating current varies synchronously with rotation of the radiation pattern of the antenna system as will be pointed out in detail hereinafter. T he modulating wheel is driven through gearing I2 by a synchronous motor I3 which is (30 in turn supplied from a three phase power source Potential is supplied to the anode cathode circuits of thermionic amplifiers 5 to 8 inclusive by means of a voltage rectier I5 which may be u; supplied from any source. The aerial described above, when energized in the manner thus far 'set forth, will radiate a xed field. Applicants invention, however, 'requires theproducton of an unsymmetrical rotating eld andv theappara- 'i0 tus to produce -.such a eld'will now be described.

In order to vary cyclicly the amplitude,of.th e.l potential applied to tht' anode 4cathode 'circuits of amplifiers 5,. 6 and I connected to frame aerials I, 2 and 3 respectively; a three' phase nated. In this modification in which the aeriai system is similar to the system of Figure 2, the rotatable goniometer pol 34 is coupled to inductances 3|, 32, and v33 which are in circuit with aerials I', 2 and 3 respectively. The inductances 3|, 32 and 33 are fixed at 120 degree angles with respect to each other as in Figure 3. In this modification, however, the coils 3|, 32 and 33 feed directly into the aerials 2" and 3 respec statement of such operation is thought unneces sary here. A

If desirable, the energizing apparatus and the driving moans of the modification shown in Figure 4 may be used to energize an aerial system of the' type shown in Figure 3, and comprised of the loops I, 2 and 3 symmetrically spaced with reference to the vertical aerial 4, without departing from the spirit of the present invention. s The operation of a system as proposed will follow as a matter of course from an understanding of the mode of operation of the modification described and illustrated heretofore.

All of the above described modifications may be especially adapted to use with a receiver which is used to receive both telegraph and telephone signals from two transmitters on the same carrier frequency since by insuring that field winding 34 is rotated slowly as for instance about two rotations per second and that a low pitch modulator generator wheel 2| is used as for example one generating a pitch from 150 cycles per second to 250 cycles per second or less, a receiver may be used having audio frequency filters, which separate the band of 150 to 250 cycles for use on the course indicator and allow frequencies above 250 cycles to pass to the operators ear phones for ordinary telephone conversation or tone telegraph reception. Thus my system can be used with very little addition to the equipment needed on the plane or ship for ordinary communication purposes.

Figure 5 shows a curve characteristic of the field radiated bythe aerial systems of the present invention which field rotates around the system. 'Ihis curve is n ot meant to be accurate but is merely illustrative of the general form of the field radiated. y

In Figure 6, the frequency ofthe modulation pitch generated is plotted with respect to rotations per second of the loop. In this curve which is not to be construed to limit applicants invention in any sense the modulation frequency range is 150 cycles per second to 250 cycles per second and it is assumed that thefield ofthe aerial system isl rotating about said system at two complete rotations per second. As `will be seen, on each rotation of the radiated pattern the pitch modulating frequency impressed on the carrier will vary from 150 cycles per second to 250 cycles per second. It will be -readilyseen froml this that a receiver located at any point on the compass with respect to the aerial system will indicate in the output circuit thereof during each rotation of the radiation pattern all of the pitch frequencies except one, that is, the one characteristicof the null point of the curve. The ab- "sence of this frequency will, of course, indicate Y v the direction of the antenna system. It will be understood that the frequency of the pitch generator', or-of the rotation of the radiation pattern or both may be'altered without departing from` .5

the spirit ofy the invention.

Any type of radio receiver known today which includes a rectifier or detectorl followed by an audio frequency amplifier can be utilized to'receive signals transmitted by the above described l0 l aerial system. All that is required is to connect in the output circuit thereof a device as illustrated in Figure l of the drawings. This indicating apparatus comprises, as shown, a reed-indicator having a plurality of reeds 4| each responl5 sive to a different frequency arranged so that the. frequencies follow each other in succession from minimum to maximum. .The reeds are mounted in a closure member 42 for vibration in a radial direction. Member 42 also carries a form 43 retained fixed with respect to 42 by means of a bolt 44 passed through an opening in said-form 43 and closure member 42 and retained therein by means of a nut 45. The support 43 carries an audio frequency magnet coil 46 which is connected 25 in the output circuit of the receiver.l This winding'46 will set up a field of varying audible frequency to which the reeds 4| will respond successively. The field built up by winding 46 will be characteristic of the nature of the modulating pitch generated by the pitch generator. Accordingly the response of the reeds` 4| to said field will be, characteristic of the modulation pitch. The indicator may be mounted in any appropriate position as on the instrument board in the cockpit by means of fasteners passed through openings 41 in the flange 48 on the closure member 42. Generally the N'and S points fall along a line parallel with the center line of the aircraft.

A circular scale on the periphery of the ring 40 on 42 may be calibrated as shown in Figure 7 to give directly the-direction from the receiver to the beacon station.

The indicator has been shown with all reeds responding more or less .except several adjacent N, 45 which have little or no motion, thereby indicating that all modulating. frequencies interposed on the rotating carrier are present in the receiver except those to which the reeds not in motion respond. These reeds indicate the position of the source of the signals when' the null point is used to determine direction. In case maximum signal is used to determine direction then a sharp maximum is radiated and one or more of the reeds respond freely to one or more of the modulating frequencies superposed on the carrier at the point of maximum radiation, thereby indicating the position of the receiver relative to the source.

In Figure 8 is shown a novelreceiver to be used 60 to receive ysignals from an aerial system of the type Vdisclosed above simultaneously with the reception of other signals as, for instance, weather signals, time signals, etc. The receiver comprises an antenna 50 connected through a receiver 5| to 65 ground. The receiver 5| includes the necessary v5.ternating current from thethreelmasepnwu' supply Il whichdrivesthesynchrmousmotor connected with the variable pitch modnlahm commutator wheel Il. ternatingcin-rentfromthesolncellandthearrangementoftheprimaryandsecmrywindingsofthetransformerferredtoaboveislnef- Aemblysuchastoinsurealmostliilil,amplitude frequency emitted at the instant that the null point ofthecardiodispoinidngwnnithereceiver.

from the receiver thatis receiving the thenonereedoranarrowbandofreedsizmed tothe modulating frequency or superposedon thecarrier atthepdnt of radiationwillvibrate freely,therehyindi|nt ingthedirectionoftheradiatlngsystu.

Inreceiversinwhichtliereedinrllcatolisnotvv usedthetoneofthesignalswlilhe characterisicofeachpointofthendialing temandwillallappearin receiver-m rotation ofthe indicate tothe operator patternucqitie ofthercceiver tionwithrespecttotheradiatlngsystem.

InFigureiiisshownanaerlalsydamr may-beusedinplaceoftheaexhl'systen Flgurel.

ispreferablyspacedonequarterofawavelurgth from themidpointofeachsideottheu'iangle. The radiation iieldofthisaerlalsystmisdhec- Vtiveinthesamerespectastheaaerlaiayatelliciis-o.

-currentsuppliedtotheotheraeriak 1Whereforanyreasonitispreferahletousean energizing circuit other lownin Figure l an aerial systun substantially as dia- 'closedinFig'urelmaybeenergiledtinmiha circuit'a'sshowninli'igureinwhichh'ameau'iah I,2and3andverticalaerial4areeadi ena-dnd bymeansof thermionicampiiile`ral,i,'|andl respectively which areas disclosed in emneeiim -withFigurelchexcitedthmhathel-mimic amplifier andmodulatorQwhidiiaemnecteden the onehandtoamasteroecillator Ilwhichsupplim the constant control frequency and on the othu' hand to a variable pitch generator 2| which my be similar to the commutator modulator of ligure l-or may be any'known audible frequency litdi generata' in general use today `which will 5 operate over the demred frequency range. The oscillations generated hy the masteroscillator Il myhemaintainedconstantby meansofacrystal orby long line frequency control as illustrated in my copending application #400,489 illed October 10 1B, 1929 now Patent 1,945,546 issued Feb. 6, 1934. The tbermionic amplifier I, which energizes the verticalaerial4.isconnected directlyto the thermionic amplifier and modulator 8. -The therminnie amplifiers' 5, i and Lhaving their output 15 circuiisconnectcdtoaerials I, 2and3respectively, have their input circuits associated with windings Il, 32 and 33 respectively. windings 3|, 22 and 33 are med preferably at 120 degree angles with to eachother and are-'arranged to be20 successively to a winding 34 connected with the output circuit of. the thermionic amplil Y 'ner and modulator 9. The winding 34 is symmounted adjacent windings 3|. 32 and 'on a shaft rotated by means of a drive motor 25 3S through reduction gearing 3l.

Anode potential is applied to the output circuits of thermionic amplifiersi, i, 1 and l by means of a; high voltage generator or rectier i5 inamannersomewhatsimilarto thatwhich it was applied to the corresponding amplifiers of VPkumel. InFigln'eltheamplltudeofthe potenth! eifecive on the anodes of the thermionic is modulated by means of alternating currmtfromathrce phasesource. In the pres- 35 cnt arrangement the potential applied to the loops I, 2 and I isvaried successively and progresslvely between limits by rotation of theciil with respect to coils 3|. A32 and`23. Rotating coil 24 with reference to the aforesaid 40 coiisvaries the coupling between the rotating coil Mandthexedcoilsl, and 33,cyclicly. .This

results in vmilicyclicly the amplitude of the high oscillations introduced into the input circuits of thermionic ampliers 5, 6 and 'i 45 This, in the manner pointed out in detail above in connection lwith Figure 1 causes meaniennasystems I, 2,3and4toradiatearoand 33 in the present installations are set at 120 50 degrees with respect to each other andthe coil Il B mounted for rotation symmetrical with re- VspeottolLnand. angle. 4Theissuchthatthecentralaa-ialV Variable pitchrgenerator'2l rotates synchronousb with the rotation of coil 34. This results tint at any and every point on the compass where areeeinrmaybelocated the signal received will indicate during each rotation of the radiation patta'nahout the aerial system all of the frequencies generated by tle variable pitch generator 2l ex- 60 ceptmewhichwillindicatethedirectionofthe Incasennximumslgnalreception isusedto de- .termine direction, the presence of a particular mcdnlaoni'requency or a band-of modulation 65 inthercceiverwillindicate the direction'of the som'ce. Y y

The operation or! this modification is'to a great extent simihr to the operation 'of the m'odiilcation shown in Figure l. A further description of the neemt invention and `of the operation thereo'is thought nIn the modification shown in Figure 4-the ne-l cessity of the amplifiers i, I..` and I and ofthe recliner andt'heirassociatcdcircuitsiselimi- 75 pass substantially all of the audible frequencies above the band passed by the band pass filter 52,

in circuit with an indicating device 54, which has been shown for purposes of illustration as a telephone. l In actual practice thepresent invention contemplates the use of several 'beacon systems, as described above, located at different points and each radiating different carrier waves, allof the carrier waves being modulated by the same band of modulation frequencies.

An operator of a rec e'iver,as described above,

may then. tune the receiver to several different beacons successively and by a, 'process of triangulation determine his exact position. Simultaneously the operator may be receiving other y information as to weather conditions, etc., on the phones 54.

In all of the beacon systems described above it is necessary that the phase and frequency of the transmitted -radiations be maintained constant, and free from error due to any causesas, for instance, ice orithe antennas.

complished in accordance with the present-invention by the use of a receiving instrument at a little distance from the transmitting antennas.

'Ihe instrument may actuate an alarm or actuate means to automatically make the necessary phase or frequency correction at the transmit- Having thus described my invention, I claim:

1. In directional radio apparatus the combilation of an aerial system including a plurality of frame aerials fixed at an angle with respect to each other, a vertical aerial, a source of oscil y lations, an amplifier iinterposed between each of said aerials and said source of oscillations, means for cyclicly Varying the amplitude of the oscillations impressed on said frame aerials, and means actuated 4in synchronism with said cyclic amplitude varying means for variably 'modulating the oscillations generated by saidsource.

2. In radio Aapparatus for producing a rotating unilateral held, a plurality of frame aerials located at an angle with respect to each other, a vertical aerial, a source of high frequency oscillations, means for connecting each of said aerials to said source, means for impressing modulations on said oscillations, the frequency of which modulations is characteristic of the position of said field when rotated, and means for varying successively between certain limits the amplitude of the oscillationsimpressed on the frame aerials to produce rotation of said field.

3. Apparatus as claimed in claim 2 in which the modulating means and the amplitude varying means are actuated synchronously.

4. The method ofv communication which .in-

cludes the steps of producing a rotating energy field which maybe represented by a cardioid curve which rotates; impressing on said .field frequencies, each narrow b'and of which is characteristic of the position of rotation of said field and receiving energy from said rotating field and producing an indication of the narrow band of frequencies not present in said received energy.

5. An aerialV system including a plurality of fixed frame aerials, a radiogoniometer having a plurality of field coils. each of said eld 'coils being connected to one of said frame aerials, a' vertical aerial symmetrically located with respect to said frame aerials', a master oscillation generator connected te seid vertical aerial and te a movable coil in said radiogonioineter, a 'modu- This is acof which is connected with one of said rst named aerials, a movable coil inductively coupled to said xed coils, a carrier frequency. generator connected to said rotatable coil 4and to said additional aerial, an amplifier in said conl5 nection, va variable modulation frequency generator connected to said amplifier, and common means for driving said generator and said movable coil.

7. A directive transmission system including aplurality of fixed frame aerials, a vertical aerial symmetrically located with respect to said frame `aerials, athermionic amplifier connected with each of said aerials, a high frequency generator connected with each of' said amplifiers, a vari- 25 able modulation frequency generator connected with said oscillation generator, a source of direct current for energizing each of said amplifiers and means for varying the amplitude of the effective y potential on each of the ampliers connected to the frame aerials.

8. An arrangement, as claimed in claim 7, in which the amplitude varying means and the Y modulation frequency generator are operated in synchronism.

9. A directive aerial system comprising a plurality of vertical aerials symmetrically placedv with reference to each other and to. an additional vertical'aerial,` a plurality of thermion'ic ampliers, each having an anode circuit connected with one of said aerials, a source of' direct current for energizing each of said ampliers, a Ahigh frequency generator connected connected through an amplifier to each of said thermionic amplifiers, a variable pitch generator Aconnected to each of vsaid amplifiers and `means for varying cyclicly the amplitude of the voltage oscillations in the output circuits of the amplifiers associated with said rst named aerials in synchronism with. frequency variations in said modulation generator.

10. The method of producing a continuously rotating unilateral eld of -radiant energy on which v v I modulations characteristic of the position of ro-' tation of said field are impressed, which includes V the steps of, generating high frequency oscillatory energy, radiating said energy in a plurality 'of' directive elds and-in a non-directive field, said fields being overlapping, modulating the amplitude of the oscillatory energy in said directive fields cyclically to produce rotation of the energy representative of the combined fields, impressing onsaid highfrequency oscillatory energy oscillations of audible frequency, and varying the 'frequency of said oscillations of audible fre- 65 quency continuously between 'certain limits. 11. A method as recited in 'claim 10 in which the variations inthe amplitude ofthe high frequency oscillatory energy and the variations in the frequency of the audible frequency oscillations are synchronous.

12. The method of producing a continuously rotating fieldA of modulated energy which includes the steps of, producing acontinuous rotary. directive field of high frequencyoscillations.

CIIv

'or uniform eld of high frequency radiant energy,

producing a directional or nonuniform field of radiant energy which rotates continuously, superimposing said fields to produce a. continuously rotating unilateral iield, and impressing on said first named high frequency elds a continuously varying tone frequency.

14. The method of direction nding by radio which comprises, generating high frequency oscillations, dividing said high frequency oscilla tions into several portions, producing a continuously rotating nonuniform or directive radiant enzrgy field with one of saidl portions, producing a uniform or nondirective eld of radiant energy with the other of said portions, the energy in said last named field being in phase with at least part of the energy in said first named field, and impressing on said energy modulating frequencies which are characteristic of the position of rotation of said first named field.

15. A method as recited in claim 14 which includes the steps of absorbing energy from both of said clds, and demodulating said energies to render the modu1ating frequency which is representative of the direction from which said energies were received.

CLARENCE W. HANSELL. 

